Noob question, making world transparent

So I want to put logo in real world picture (will composite in After Effects) I want the world to be transparent, I’m going to put a plane underneath the logo with only shadows marked.

If you want to render an image with the background transparent, select an image format that can handle an alpha (such as png). Select RGBA in the format to give the image an alpha channel and Premul in the render panel. Render and the image will have a transparent background. View in the UV/Image editor and select the ‘Draw Image with Alpha’ button in the header to view.


thank you thank you!